Comparative distribution of NURR1 and NUR77 nuclear receptors in the mouse central nervous system.

NURR1 and NUR77 are members of the nuclear receptor superfamily of transcription factors. Both proteins can interact with common enhancer elements to regulate target gene expression. In order to establish whether both transcription factors are likely to regulate overlapping genes, we have used an in situ hybridization approach to relate the constitutive expression pattern of these mRNAs with functionally defined regions of the adult mouse brain. By Western analysis, NURR1 mRNA expressed by brain cells appeared to be translated. Here we show that both transcripts display a differential but partially overlapping pattern of expression within the central nervous system (CNS). The expression of NURR1 is more restricted than NUR77 and is localized predominantly in sensory neuronal structures associated with the limbic system and in the cerebellum. In contrast, the expression pattern of NUR77 is more widespread. Positively staining cells for NUR77 appear to overlap with NURR1-containing cells in the limbic system and cerebellum, suggesting overlapping roles for these proteins in mediating behavioral and cognitive function as well as equilibrium maintenance. However, the differential expression of NUR77 in motor areas of the cortex and basal ganglia suggest a selective role for this transcription factor in regulation of motor function at the constitutive level. Our data indicates that these nuclear receptors are likely to have both shared and independent gene regulatory roles in neuronal cells.